Small-for-gestational age and preterm birth across generations: a population-based study of Illinois births.

Small for gestational age (weight for gestational age <10th percentile, SGA) and preterm birth (<37 weeks, PTB) are the major determinants of infant mortality rates and racial disparities therein. To determine the generational inheritance patterns of SGA and PTB among non-Hispanic Whites and African-Americans. Stratified and multivariable binominal regression analyses were performed on an Illinois transgenerational dataset of White and African-American infants (1989-1991) and their mothers (1956-1976) with appended US census income information. Former SGA White mothers (N = 8,993) had a twofold greater infant SGA frequency than former non-SGA White mothers (N = 101,312); 14.4 versus 6.9 %, RR = 2.1 (2.0-2.2). Former SGA African American (N = 4,861) mothers had a SGA birth frequency of 25.7 % compared to 16.1 % for former non-SGA mothers (N = 28,090); RR = 1.5 (1.5-1.6). The adjusted (controlling for maternal age, education, marital status, parity, prenatal care usage, cigarette smoking, and hypertension) RR (95 % CI) of infant SGA for former SGA (compared to non-SGA) White and African-American mothers equaled 2.0 (1.9-2.1 and 1.5 (1.5-1.6), respectively. The adjusted RR (95 % CI) of infant preterm birth for former preterm (compared to term) White and African-American mothers were 1.1 (1.0-1.2). The findings were minimally changed among mothers with a lifelong residence in impoverished or affluent neighborhoods. In both races, approximately 8 % of SGA births were attributable to maternal SGA. There is a transgenerational association of SGA but not preterm birth among non-Hispanic Whites and African-Americans. In both races, a similar proportion of SGA births are attributable to maternal SGA.